The invention herein pertains to water purification using ion exchange resins and particularly pertains to a continuous loop purification method using a control valve for selective purified water withdrawal.
Water is considered highly purified when it has a minimal electrical resistance of 18 meg ohms per centimeter at 25xc2x0 C. Water of such high purity can easily become contaminated and therefore circulation through a loop has frequently been used with various devices such as laboratory faucets and the like. Constant circulation insures purity while preventing stagnation which accommodates bacterial growth. High purity water is of vital importance in today""s manufacturing plants that produce electronic circuitry, chips and other high tech components and equipment. Also, high purity water is a must in kidney dialysis and many other medical procedures. Thus, while it is not difficult to produce 18 meg ohms water, it is difficult to constantly maintain this purity over long periods of time for use on an xe2x80x9cas neededxe2x80x9d basis.
Based on the constant need for high purity water, the present invention was conceived and one of its objectives is to provide a continuous loop purification method which will allow the user to tap as much or as little 18 meg ohms water as needed for a particular application.
It is still another objective of the present invention to provide a water purification method which provides water of high purity in a continuous loop using ultraviolet light and ion exchange.
It is yet another objective of the present invention to provide a control valve to allow high purity-water to be selectively withdrawn therefrom without contaminating the remaining water.
It is also an objective of the present invention to provide a control valve which provides a manually operated spool which is both simple to use and inexpensive to manufacture and distribute.
Various other objectives and advantages of the present invention will become apparent to those skilled in the art as a more detailed description is set forth below.
The aforesaid and other objectives are realized by providing a continuous water purification loop having a manually operable control valve therein. The control valve allows the user to withdraw a selected amount of the highly purified water as the water circulates. The control valve includes a handle for manual manipulation of a central spool residing in a duct within the valve housing. The duct has a series of axially spaced, parallel grooves therealong with O-rings therebetween. The spool includes a plurality of longitudinal channels which allow water to pass from an inlet port on the housing to either first outlet or second outlet ports, or to both for as great or as little flow through second outlet port as desired. Thus, the spool can be regulated so purified water which does not exit from the second or use outlet port remains in the loop for continued purification at a flow rate of approximately 0.75 gal/min. By manually selectively turning the spool a very small quantity of purified water can be withdrawn as needed (up to 0.75 gallons/minute) for example to a faucet, while allowing any undrawn water to continue along the loop. The control valve has only a few parts and prevents stagnation which can lead to biological growth and impurity of the water.